1. Field of the Invention
The present invention relates to a sheet supplying device for use in a copier, a printer and the like.
2. Description of the Related Art
An apparatus supplied with a sheet material, for example, a copier which is supplied with copying sheets, such as paper, is provided with a sheet supplying device. The sheet supplying device is provided with a plurality of sheet supplying cassettes with each cassette corresponding to a plurality of sizes of the sheet. A lateral transport for transporting a sheet in the direction of its width is more preferable in view of the transport speed than a longitudinal transport for transporting a sheet in its longitudinal direction. There exists a copier which enables the lateral transport of even large-sized sheets such as B4- and A3-sized sheets.
On the contrary, in order to transport such a large-sized sheet in the lateral direction, it is required that the photoconductive drum, the transport roller, the transport path, etc. in the copier are also large, resulting in the increase of size and cost of the copier. Therefore, a method is preferably used for transporting a large-sized sheet, such as B4-, A3-sized sheets, in the longitudinal direction, while transporting a small-sized sheets, such as sheets of not larger than A4-size, in the lateral direction.
However, in the case, for example, where the copier has a variable magnification function for reducing or enlarging an image, the copier needs B5R- and A4R-sheet cassettes for a longitudinal transport in a reduction copying operation, and further needs B5- and A4-sheet cassettes for a lateral transport in a normal copying operation in consideration of the transport speed. If such various types of cassettes are used in the copier, it is required that the sheet supplying device shall be large to accommodate all of those cassettes, or that one of those cassettes shall be selected and exchanged at the sheet supplying device according to the purpose of each copying operation. As a result, this makes the copier large and thus increases the cost, or complicates the copying operation and thus increases the operation time.
Thus, in order to solve the above problem, a conventional sheet supplying device has been proposed, wherein a common cassette is used for supplying a same sized sheet in two different transport directions, for example, a common cassette for B5 and B5R and a common cassette for A4 and A4R are used, and the switching between the lateral transport and the longitudinal transport is done by turning the cassette, as disclosed in the Japanese Patent Application Laying Open (KOKAI) No. 56-59245, No. 59-123859, etc.
However, in the above conventional supplying device, in case that the same sized sheets are stacked in both a turning cassette, which is capable of turning between a longitudinal transport position for transporting the sheet in the longitudinal direction and a lateral transport position for transporting the sheet in the lateral direction, and a fixed cassette, which is fixed at either the longitudinal transport position or the lateral transport position, when a sheet of this same size is selected, it is not considered which cassette should be selected for supplying the sheet therefrom in view of a smooth and flexible operation of the copier. Therefore, it has been desired to develop a device capable of setting the proper order for selecting a cassette.